1. Field of the Invention
The present invention relates to a method for controlling a final pile diameter in a cast-in-place pile formed by solidification within the ground by a jet process which includes injecting a settable mixture in a high pressure jet flow into the ground.
2. The Prior Art
The method is known for forming a cast-in-place pile formed by solidification within the ground of a settable material by injecting a settable material in a high pressure jet flow, for improving a soil condition.
As representative such methods, a jet grout method and a chemical charging pile method are discussed below.
The jet grout method is a method for forming a cast-in-place pile formed by solidification of a settable material by injecting a hardening agent in fluid which fills a void created by cutting the ground with the fluid in a super-high pressure jet flow surrounded by air. The chemical charging pile method is a method for forming a cast-in-place pile formed by solidification of a settable material within the ground by injecting a hardening agent into the ground at a super-high pressure while cutting the ground with its destructive force.
Now, in such a known soil improvement method, at an injection of settable material in a high pressure jet flow into the ground, a throw-distance of the material in the jet flow, from a central pipe which injects the settable materials, depends on soil condition and soil properties (strength, water content, void ratio). It was a practice which was preferred in the prior art to produce the final diameter of the cast-in-place pile so that it is somewhat larger than actually required by injecting of water or injecting of the hardening agent with an excessive power.
In the prior method for providing a final diameter of a cast-in-place pile which is somewhat larger than is required by injecting of water or of a hardening agent with an excessive power, there are problems such as loss of material and outflow of a substantial amount of slime, etc.